/*
 *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include <memory>
#include <vector>

#include "common_video/h265/h265_common.h"
#include "common_video/h265/h265_vps_parser.h"
#include "rtc_base/bit_buffer.h"
#include "rtc_base/logging.h"

#include "rtc_base/bitstream_reader.h"

namespace webrtc {

    H265VpsParser::VpsState::VpsState() = default;

    // General note: this is based off the 06/2019 version of the H.265 standard.
    // You can find it on this page:
    // http://www.itu.int/rec/T-REC-H.265

    // Unpack RBSP and parse SPS state from the supplied buffer.
    absl::optional<H265VpsParser::VpsState> H265VpsParser::ParseVps(
        const uint8_t* data,
        size_t length) {
        return ParseInternal(H265::ParseRbsp(data, length));
    }

    absl::optional<H265VpsParser::VpsState> H265VpsParser::ParseInternal(
        rtc::ArrayView<const uint8_t> buffer) {
        BitstreamReader reader(buffer);

        // Now, we need to use a bit buffer to parse through the actual HEVC VPS
        // format. See Section 7.3.2.1 ("Video parameter set RBSP syntax") of the
        // H.265 standard for a complete description.
        VpsState vps;

        // vps_video_parameter_set_id: u(4)
        vps.id = reader.Read<uint32_t>();

        return vps;
    }

}  // namespace webrtc